From: Todd Benson <caduceass@...>
Date: 2007-10-25T00:21:47+09:00
Subject: Re: pop/push, shift/unshift

On 10/24/07, Todd Benson <caduceass@gmail.com> wrote:
> On 10/24/07, Bob Hutchison <hutch@recursive.ca> wrote:
> >
> > On 24-Oct-07, at 9:03 AM, Todd Benson wrote:
> >
> > >   def dequeue
> > >     @list.shift
> > >   end
> >
> > Save yourself some grief, do it this way:
> >
> > def dequeue
> >    tmp = @list[0]
> >    @list[0] = nil
> >    @list.shift
> >    tmp
> > end
> >
> > Cheers,
> > Bob
>
> Bob, I can only guess that the grief you are talking about has
> something to do with memory management, but I don't see it.
>
> Can someone explain -- with the code above -- why tmp does in fact
> _not_ take on NilClass?  I think it would be good info for newbies.
>
> Todd

Okay, I guess I can answer my own question.  Binding is resolved when
an operator like '=' is interpreted, especially with immutable objects
(like Fixnum).

a = 1,2,3
puts a[0].__id__
#output => 3
b = a
puts b.__id__
#output => 3
a[0] = 7
puts a[0].__id__
#output => 15
puts b.__id__
#output => 3

For the newbies out there, keep this in mind.  The name b put on
a[0]'s shoes and kept them on.  Somebody correct me if I'm wrong.

Todd